GENOMIC APPROACHES TO IMPROVING TRANSPORT AND DETOXIFICATION OF SELECTED MINERAL ELEMENTS IN CROP PLANTS
Location: Plant, Soil and Nutrition Research
Title: Elucidating the Molecular Determinants of Aluminum Tolerance in Sorghum, Maize and Rice
Submitted to: Plant and Animal Genome Conference
Publication Type: Abstract Only
Publication Acceptance Date: December 17, 2007
Publication Date: January 15, 2008
Citation: Kochian, L.V., Magalhaes, J., Liu, J., Pineros, M., Maron, L. 2008. Elucidating the Molecular Determinants of Aluminum Tolerance in Sorghum, Maize and Rice. Plant and Animal Genome Conference.
Aluminum (Al) toxicity on acid soils represents a major constraint for crop production worldwide, thus understanding the genetic and molecular mechanisms of Al tolerance has been a major focus for a number of laboratories. Here, we report on the progress made from our Generation Challenge Program grant on the identification and characterization of Al tolerance genes and associated physiological mechanisms in sorghum, maize and rice. With regards to sorghum Al tolerance, we have cloned via high resolution mapping a candidate Al tolerance gene, AltSB, that is a novel, Al-activated citrate transporter involved in the primary mechanism of sorghum Al tolerance. Evidence will be presented verifying that AltSB is a major sorghum Al tolerance gene. Also, sequence analysis of the parental AltSB alleles and the promoter region from selected members of a sorghum diversity panel, combined with determination of AltSB expression, Al tolerance and root citrate exudation indicates that differences in gene expression are a major determinant of sorghum Al tolerance. This research also has allowed us to identify superior AltSB alleles and work is now underway to use this information to facilitate improvements in sorghum Al tolerance via marker-assisted selection. In maize, we have employed an interdisciplinary approach based on maize root tip gene expression profiling, analysis of maize homologs of the wheat (ALMT1) and sorghum (AltSB) tolerance genes, and knowledge of physiological mechanisms of maize Al tolerance to identify candidate maize Al tolerance genes. Subsequent association and linkage analysis of these candidates has identified a number of putative tolerance genes.